Soft errors involve changes to stored data, as opposed to changes to the physical circuit itself. Soft errors may be caused, for example, by alpha particles from radioactivity in packaging materials and/or from the impact of neutrons from space. It is known to carry out accelerated testing on electronic circuits to estimate the effects of soft errors, by deliberately exposing the circuits to radiation.
For example, U.S. Pat. No. 7,238,547 of Zabel et al., the complete disclosure of which is expressly incorporated herein by reference in its entirety for all purposes, discloses packaging integrated circuits for accelerated detection of transient particle induced soft error rates. An IC device is packaged for accelerated transient particle emission by doping the underfill thereof with a transient-particle-emitting material having a predetermined, substantially constant emission rate. The emission rate may be tunable. In one aspect, a radioactive adhesive composition is provided for bonding a semiconductor device to a chip carrier. The radioactive adhesive composition is made from a cured reaction product including a resin and a filler, and may be reworkable or non-reworkable. Either the resin or the filler, individually or both together as a mix, are doped substantially uniformly with the transient-particle-emitting material, thereby putting the transient-particle-emitting in close proximity with the IC to be tested. The underfill is formulated to have a stable chemistry, and the doped particles are encapsulated, so as to contain the emissions. Accelerated transient-particle-emission testing may then be performed on the IC in situ to provide accelerated detection of soft errors.